1. Field of the Invention
The present invention relates to a washer, and more particularly to a method of and an apparatus for controlling a washing operation of a washer.
2. Description of the Prior Art
FIG. 1 is a block diagram of a conventional apparatus for controlling a washing operation of a washer. As shown in FIG. 1, the control apparatus includes a water level sensing unit 1 for sensing an amount of a water supplied in a washing tub of the washer, a turbidity sensing unit 2 for sensing the turbidity of a washing water contained in the washing tub, and a clothes sensing unit 3 for sensing an amount of clothes. A microprocessor 4 is connected to all the sensing units 1, 2 and 3. The microprocessor 4 serves to compare data sensed by the sensing units 1, 2 and 3 with corresponding reference data, determine various information required to control the washer such as a washing time, the kind of a detergent, a detergent amount and a water flow intensity, and outputs the determined information. Connected to the microprocessor 4 are a storing unit 5 for storing reference data experimentally obtained and a display unit 6 for displaying a condition of the washer operated in an operation mode selected by a user. A switching unit 7 is also connected to the microprocessor 4. The switching unit 7 outputs control signals for actuating a motor 8, a water supply valve 9 and a water drain valve 10 under a control of the microprocessor 4.
As shown in FIG. 2, the turbidity sensing unit 2 includes a D/A converter 21 adapted to convert a control signal PWM outputted from the microprocessor 4 into an analog signal. To the output of the D/A converter 21, a transistor 22 is coupled which is activated by the analog signal from the D/A converter 21. A diode 23 is connected to the input of the transistor 22. When the transistor 22 turns on, the diode 23 becomes a conductive state and thus emits light. A transistor 24 is also provided which receives the light emitted from the diode 23 via a polluted washing water. To the output of the transistor 24, an A/D converter 25 is coupled which converts the amount of received light into a digital signal. The digital signal is sent to the microprocessor 4.
The amount of light received in the transistor 24 is varied depending on the turbidity of the washing water. The diode 23 is a photosensor for converting a light into an electrical signal.
As the user selects an operation mode of the washer using the display unit 6, a corresponding mode signal is fed to the microprocessor 4. Thereafter, when the microprocessor 4 receives data indicative of the current condition of the washer, from the water level sensing unit 1, the turbidity sensing unit 2 and the clothes amount sensing unit 3, it compares the received data with reference data.
The results of the comparison achieved in the microprocessor 4 are sent to the motor 8, the water supply valve 9 and the water drain valve 10 via the switching unit 7, respectively. Accordingly, the motor 8, the water supply valve 9 and the water drain valve 10 via the switching unit 7 are actuated according to the comparison results, respectively.
For instance, when a washing mode signal is received in the microprocessor 4, it is then outputted as a control signal PWM from the microprocessor 4. The control signal PWM is converted into an analog signal through the D/A converter 21. The analog signal is then applied to the transistor 22, thereby causing the transistor 22 to turn on.
As the transistor 22 turns on, the diode 23 emits a light which is, in turn, fed to the transistor 24 via the washing water.
The amount of light received in the transistor 24 is varied depending on the turbidity of the washing water and converted into a digital signal through the A/D converter 25. The digital signal is then fed to the microprocessor 4.
From the received light amount, a turbidity of the washing water is determined. Data indicative of the turbidity of the washing water is compared with reference data stored in the storing unit 5. This comparison is continued until the washer starts to operate at a stable state after an initiation of washing operation. From the results of the comparison, various information required to control the washer is determined which includes a washing time, the kind of a detergent, a detergent amount, a water flow intensity.
A turbidity ascent curve, which represents turbidity of the washing water for a period from a washing initiation point t1 to a point of time when the washer starts to operate at a stable state, is variously depicted according to the kinds of materials polluting the washing water, the kind of detergent, and a temperature of the washing water, as indicated by curves a, b and c in FIG. 3. As a result, the turbidity data has a complex characteristic.
However, the conventional washer does not take into consideration such complex turbidity data, thereby involving a high possibility of a malfunction.
In determining the kind of detergent, the conventional washer compares turbidity data sensed when a predetermined time elapses after an initiation of the washing operation, with reference data so that a liquid detergent i s determined when the turbidity data is not less than the reference data, whereas a powder detergent is determined when the turbidity data is less than the reference data. Although such a determination enables a selected use of the liquid detergent and the powder detergent, it makes it impossible to determine a detergent to be used, in terms of the manufacturer. As a result, the kind of detergent may be erroneously determined. Such an erroneous determination results in a problem that the detergent is used in an excessive amount or an insufficient amount.